1. Field of the Invention
The present invention relates to a perpendicular magnetic recording head which performs a recording action by applying a recording magnetic field perpendicularly to a recording medium plane, and a method of manufacturing the same.
2. Related Background Art
As is well-known, a perpendicular magnetic recording head has a main magnetic pole layer and a return yoke layer which are positioned with a predetermined distance therebetween on a surface (medium-opposing surface) opposing a recording medium, a nonmagnetic insulating layer interposed between the main magnetic pole layer and return yoke layer, and a recording coil arranged within the nonmagnetic insulating layer. The main magnetic pole layer and return yoke layer are magnetically coupled to each other on the deeper side in the height direction of the medium-opposing surface. When a recording magnetic field is induced between the main magnetic pole layer and return yoke layer upon energization of the recording coil, a leakage recording magnetic field occurs between the main magnetic pole layer and return yoke layer on the medium-opposing surface. This recording magnetic field perpendicularly enters a hard magnetic film of the recording medium from the front end face of the main magnetic pole layer exposed at the medium-opposing surface and returns to the return yoke layer through a soft magnetic film of the recording medium. This subjects the recording medium to magnetic recording at a part opposing the front end face of the main magnetic pole layer.
In such a perpendicular magnetic recording head, the size in the height direction (throat height) of the return yoke layer is an important parameter for improving recording performances, and thus is required to be defined appropriately. As disclosed in the Japanese Patent Application Laid-Open No. 2002-352402 and Japanese Patent Application Laid-Open No. 2004-318949, examples of methods for defining the throat height include a method of forming a positioning layer made of an organic resist material at a position yielding a desirable throat height retracted from the medium-opposing surface, and a method of forming a return yoke layer having a desirable throat height by plating, The latter method typically fills the deeper side in the height direction of the return yoke layer with an inorganic nonmagnetic insulating material layer and flattens the upper face of the nonmagnetic insulating material layer and the upper face of the return yoke layer by polishing.